Light Duty: Time For Tire Pressure Maintenance Systems

by Scott De Laruelle On Mar 13, 2008

Under-inflated tires have caused fleets more problems than your average B-movie gremlin—that is, until modern tire pressure systems and the recent motor vehicle standard hit the block. Could the feds actually be helping your shop’s bottom line?

Failure to properly maintain tires can set off a chain reaction of financial troubles for a fleet, including reduced fuel efficiency, handling, driving comfort and tire life as well as increased chances of accidents—more than 500 people are killed in the U.S. every year in accidents cause by tire defects, according to the National Highway Transportation Safety Administration (NHTSA).

Tire failures and fatal accidents were at the core of NHTSA’s regulation requiring all new 2008 model year passenger cars and light trucks to have a tire pressure monitoring system (TPMS) to alert drivers when the pressure in one or more tires falls 25 percent below the vehicle manufacturer’s recommended inflation pressure or a minimum activation pressure specified by NHTSA, whichever is higher.

This is the latest federal act in a series that started with the TREAD Act in 2000, enacted by Congress in response to reported tire failures caused by tread separation from certain Firestone tires installed on Ford SUVs and trucks that—according to NHTSA—resulted in about 268 fatal crashes from January 1991 to August 2001. In 2002 the administration mandated the systems on all new passenger cars and light trucks, but some consumer safety groups challenged the rule in court over concerns that certain systems would not sufficiently detect tire under-inflation. In response, NHTSA issued its new rule in 2005 that 20 percent of affected vehicles must have the systems for model year 2006, 70 percent for 2007 and 100 percent for the 2008 models.

EXTRA WARNING

Checking tire pressure should be one of the most basic maintenance rituals for fleets of any size, yet a Federal Motor Carrier Safety Administration (FMCSA) study showed less than half of the commercial vehicles were within five PSI of target pressure, and about 7 percent were under-inflated by 20 or more. As the saying goes, accidents on the street happen because of accidents in the shop, and tires are no different. Left untended, it is only a matter of time before tire materials are weakened to the point of failure—then it’s a matter of hoping your driver can keep their load on the road and get out of harm’s way without causing an accident. TPMS can give your drivers—and yourself—a little extra warning that can go a long way.

Though there are traditionally two kinds of systems—direct and indirect—most available commercially today are direct. These use pressure sensors in each wheel that tie into an on-board computer that warns drivers when any tires drop below 25 percent of the recommended level. Most OEM and aftermarket systems attach their sensors to special tire valves. These can detect gradual changes over time and in some cases provide a dashboard display to observe pressure readings.

Indirect systems warn drivers when a tire has lost at least 25 percent of recommended inflation compared to the other three, using ABS wheel speed sensors to measure differences in tire revolutions. These systems cannot warn drivers which tire is going flat, or if all four tires are losing pressure at a similar rate.

TPMS are relatively easy to install and maintain, since many vehicles already have wheel speed sensors for ABS or electronic stability control systems. There is some variety, as OEMs do have some options on how to fit these systems within NHTSA’s regulations. FMCSA’s stance on the systems was to “strongly suggest that the savings potential from tire pressure monitoring and automatic inflation systems could support the purchase prices of systems and products currently in the marketplace. The challenge for the supplier community is to prove reliability and reduce or eliminate added maintenance for the systems themselves.”

ADVANTAGE PRESSURE PRO

In the tire pressure system business for the past 16 years, business has definitely picked up in the past few for Advantage Pressure Pro, says director of marketing Vanessa Zaroor, because many fleet officials are tired of rising costs and their technicians’ overlooking proper tire maintenance.

“Now instead of us banging on their doors, saying, ‘Here’s what we can do for you,’ people are starting to come to us,” she says. “When we start talking they realize we can integrate with other products—if they are running a fleet maintenance system for their trucks or vans, we can tie into a lot of other things and piggy-back those readings via satellite or cell services back to their home base. A (smaller) fleet can call a mobile van and say, ‘You’ve got this tire low, you need to start doing something about that.’”

The rising costs of fuel, replacement parts and accidents have seemingly forced the hand of some shop managers who may have been putting off the costs of a big conversion—costs that now are looking a lot more affordable.
“People are finally starting to grasp it, that’s what caused the difference,” Zaroor says, ticking off a laundry list of cost-savings: “Safety, and now gas—for every five pounds of pressure you’re low; you lose 3 percent fuel efficiency. If your tires are properly maintained, you can basically save up to 5 percent on your fuel efficiency. You’re going to have better handling and braking, better stability and performance, and you save fuel by not having the added resistance from a tire being low on pressure.”

Maintenance-wise, Zaroor says a good tire pressure system can make a shop work much more efficiently. While checking tires can be an overwhelming task for heavy-duty fleets, smaller light-duty vehicles need no less attention to detail. Tire pressure monitoring systems can also get the information straight to the managers, saving the technicians’ time for other duties unless a problem is detected.

Of course, practical safety issues of preventing tire wear, blowouts and potentially costly accidents are the main reason TPMS are gaining popularity for light-duty vehicles, where losing one of four tires could cause a dangerous loss of control.

“You hear about (blowouts) more from the (heavy-duty) trucks, because people have a negative view of them, unfortunately, but about 80 percent of all blowouts on the road aren’t due to a sudden impact; they are due to low tire pressure that builds up over time,” Zaroor says. “On light vehicle, safety is going to be a bigger reason than on (larger vehicles) because they want the fuel savings and better performance.”

TIRE SENTRY

A division of Fleet Specialties, Co., the Westlake Village, CA-based business has been selling TPMS for nearly a decade, offering products both through OEMs and the aftermarket. Bill Shore, project manager for Tire Sentry’s new TMS series, says tire under-inflation is one of the costliest problems a fleet faces, but is one that can be mitigated with a TPMS.

“Not only does it cause excessive heat buildup in the tire, creating dangerous driving conditions, but it will also shorten tire life by rapidly increasing tread wear,” Shore says. “Our system is designed for the detection and prevention of under-inflation, so it can help reduce the occurrences of accelerated tread wear, which is just one of the results. Zipper ruptures is another; over-heating and vulcanization is another, and any of those can cause a disastrous situation or just ruin the tire.”

In the end, it comes down to maintenance, and how much time and effort technicians are willing to put towards the tire. Shore says from talking with fleets, it can be a real problem.

“Regularly checking tire pressures, as they tell us, is one of the most important maintenance procedures that they have learned, yet it’s one of the most difficult to enforce,” he says. “Even the best preventative maintenance programs will find that maintenance personnel all too often overlook checking the tires—even the best preventative maintenance programs can’t prevent tire damage resulting from the loss of tire pressure while on the road.”

The Tire Sentry system uses a series of electronic valve caps, replacing the existing caps, to warn the driver when any tire has lost as little as 10 percent of normal operating pressure. It can also tie in to the truck’s other electrical systems and send information directly to the home office.

Shore says advances in microchip technology have made electronic tire pressure monitoring more affordable for fleets.
“It can be quite an asset to a fleet to monitor tire pressure in a fashion of this nature,” Shore says. “It’s just they have never had an opportunity to monitor tires automatically at a reasonable cost to them, but that situation exists now, and that is within most operating budgets to have automatic tire pressure monitoring right from the cab.”

RIGHT FIT

Light duty fleets can definitely benefit from TPMS just as much as heavy-duty fleets, Shore says.

“They are feeling the pinch in both their fuel economy situations and the continuing upper drive of tire cost, so they become more aware of what tire pressure monitoring can do,” he says. “As a result of that, we’ve come out with three new systems, dedicated primarily to the light truck market, and those can be easily installed.”

The newest wireless system plugs into a cigarette lighter and has all the electronic and display mechanisms built right into the plug, where it can monitor all the tires.

“It’s going to help them increase fuel efficiency and reduce tire maintenance costs, and one of the nice things about the system, it has low maintenance costs—all tire sensors run on battery power and ours runs on a replaceable battery,” he says. “The maintenance factor is one of the keys with just about any fleet operators, and our systems have very little maintenance required.”

Installation is very simple, Shore says, depending on the model.

“The easiest installation is with the new RC models that just plug into the cigarette lighters,” he says, “There are pedestal-mount models and most of our fleet models come with a two-inch round display that is easy to mount and those require providing 12 volts of power to it. The rest is just installing the sensors to the tires and installation is really minimal.”

OEMs - TOYOTA AND FORD

Toyota uses a direct-type system that will turn on the tire pressure warning light to warn the driver of a low tire when the pressure of a tire becomes lower than the threshold, helping to prevent premature tire wear and fuel waste. The tire pressure warning valve and transmitter is integrated in the air valve of a wheel. Each tire pressure warning valve and transmitter consists of a lithium battery, sensor and transmitter.

Kwong says tire pressure monitoring systems do not replace routine tire inflation pressure checks, however, noting that technicians should check tire pressure every two weeks, or at least once a month. He said maintenance on this system is minimal, though—once the technician initializes the system at new vehicle prep, no maintenance is required.

The current system warns a driver if one or more tires are significantly under-inflated using pressure sensors with radio transmitters on each tire. An in-vehicle receiver monitor will activate a warning light, or message in vehicles equipped with a message center. The system is used on Ford’s SUVs and trucks because of its ability to operate in four-wheel and all-wheel drive and in off-road environments.

Ford’s systems include a diagnostic function that flashes a warning light for 60 to 90 seconds when it detects a malfunction. It also uses wheel well-mounted pressure sensors to reduce susceptibility to damage when changing a tire, compared to valve stem-mounted sensors.

GET ON BOARD

According to FMCSA, there is a lack of data about tire pressure maintenance practices on commercial vehicles, so the “problem” of improper inflation is not yet well understood. As a result, many fleet officials are simply left to guess how much tire monitoring systems will help.

On the other hand, many fleets take great care in selecting a specific tire pressure for their vehicles, depending on the expected load, road conditions and weather. If tires are not properly inflated and maintained, vehicle safety, performance and fuel economy—not to mention your bottom line—will suffer.

Good managers are going to make the best use of their tools, and today’s TPMS can save fleets money on system procurement and maintenance costs, total direct costs avoided with properly maintained tires, tire installation costs, associated downtime and costs from improved safety. If you’re buying a new light-duty vehicle, you’re going to get one anyway, so you might as well get the one you want.